Demolition, drilling, detonation, building and mining work can create large amount amounts of dust. On undertaking such work, suitable breathing protection is required for workers as well as equipment that reduces the spread of dust to the surrounding air. Most drilling rigs today are equipped with a dust separator.
A dust separator for a rock drilling machine often comprises a cyclone. A gas flow that contains dust is fed into the cyclone at an angle and is rotated at high speed. The centrifugal force that arises due to the circular flow forces throws particles of dust towards the cyclone's inner wall. After the particles of dust have hit the wall, they fall down into the lower part of the cyclone. The lower part of the cyclone can for example comprise a dust outlet that can be opened using a one way valve, such as a rubber tube whose sides have been pressed together. When a lot of dust particles have collected in the cyclone, they will, due to the action of gravity, be forced through the rubber tube whose sides have been pressed together. Dust can fall into a sack or a container that is located under the cyclone, which sack or container can be emptied when the cyclone is not in use.
A double vortex is created in the cyclone when it is in use. A main vortex, that is directed downwards, carries the coarser/heavier particles of dust. An inner vortex, that is created in the lower part of the cyclone and that is directed upwards, carries the finer/lighter particles of dust to an outlet in the cyclone's upper part. The finer/lighter particles of dust are often sucked up by a dust sucker via a suction hose that is connected to the outlet in the cyclone's upper part.
The French patent application no. FR 2 479 505 discloses a device that comprises a cyclone and a centrifuge whereby the centrifuge is located upstream of the cyclone. The coarser/heavier particles of dust in the incoming gas flow will therefore have an eroding effect on the centrifuge's components. Maintenance and replacement of the centrifuge's components will therefore increase running costs.
The above-referenced French patent application also discloses a device in which a centrifuge is located downstream of the cyclone. The centrifuge's axis of rotation extends horizontally. In such an embodiment some of the dust particles will be thrown upwards out of the centrifuge and the force of gravity will again pull these dust particles into the centrifuge, which reduces the efficiency of the centrifuge and causes unnecessary wear of the centrifuge's components.